Door latch and adjustable keeper



p 2, 1952 A. R. MITCHELL 2,609,224

DOOR LATCH AND ADJUSTABLE KEEPER Filed Feb. 27, 1948 2 Sl-IEETS-SHEET 1 VWA W Attorney Sept. 2, 1952 A. R. MITCHELL .DOOR LATCH AND ADJUSTABLE KEEPER 2 SHEETS-SHEET 2 Filed Feb. 27, 1948 7 a ll finvwrammll Patented Sept. 2, 1952 DOOR LATCH AND ADJUSTABLE KEEPER Archibald Robertson Mitchell, Hornchurch,

" England Application February 27, 1948, Serial No. 11,367 In Great Britain November 11, 1946 Section 1, Public Law 690, August 8, 1946 Patent expires November 11, 1966 Claims.

1 This invention relates to door and like latches of the kind having a spring-actuated bolt withdrawable by means of a key, as for example the so-called Yale pattern latch. Such latches have many advantages and are widely used, but as at present generally constructed they afford only very limited protection against intruders. The bolt can always be withdrawn from the inner side of the door without the use of a key and it is frequently a simple matter for an intruder to break or cut away a panel of the door and thus obtain access to the operating handle on the inner side of the door. Moreover it is usually easily possible for an intruder to insert an implement between the latch casing and the keeper and press back the projecting end of the spring mounted bolt. The object of the present invention is to avoid these disadvantages while retaining the advantages of the existinglatches.

In accordance with one feature of the present invention a latch of the kind referred to is provided with a safety device which can be moved without the use of a key by operating means on the inner side or on the edge of the door into an operative position in which it renders the operating handle on the inner side of the door ineffective to withdraw the bolt, the safety device being restored to inoperative position when the bolt is withdrawn by the insertion and rotation of the key from the outer side of the door. The safety device may operate either to prevent rotation of the operating handle or to disconnect it from the bolt.

The provision of the safety device alone, while effective to prevent breaking in by the method first mentioned above, would have the disadvantage of making it impossible to open the latch from the inner side of the door once the safety device had been moved to operative position. Preferably, therefore, means operable from the inner side of the door are provided for restoring the safety device to its inoperative position, the operation of these restoring means being effected or controlled by a key, which, is preferably that of the lock itself.

' In accordance with another feature of the'invention, in order to prevent breaking in by the second of the methods mentioned above, the latch casing and the keeper of a latch of the kindreferred to are formed with ribs and grooves which come into interlocking engagement when the-door is closed and that part of the keeper with which the latch casing engages is so mounted that it can door shrinkage and door drop. The movable part of the keeper is thus retained in such close coupled relation to the latch case that no access to the bolt for the purpose of forcing it back is possible when the door is closed. This feature of the invention is clearly capable of use independently of the safety and restoring devices above referred to, but it is preferably used in combination with them, in order that protection may be afforded against breaking in by either of the methods mentioned above.

A door latch constructed-in accordance with the invention and embodying all the features mentioned above is illustrated in the accompanying drawings, to which attention is now directed for a fuller understanding of the invention and of the manner in which it is tobe carried into practice. In these drawings Figure 1 is a front elevation of the latch casing (i. e. a view taken from the side which in use is secured against the inner face of the door) with the cover plate removed, but showing a part of the bolt operating cam which is carried by the cover plate and in use is connected to the key operated shaft not shown) Figures 2, 3 and 4 are sections taken on the lines AA, 13-13 and C0 respectively of Figure 1; Figure 5 isa sectional plan of the fore end of the latch casing and of the keeper, the section being taken on the line D-D of Figure 6; Figure 6 is a sectional front elevation of the parts shown in Figure 5, the section being taken on the line E-E of Figure 5, with the upper part of the spring friction plate removed; Figure 7 is a section through the parts shown in Figures 5 and 6, taken on the line F--F of Figure 6.

Referring first to Figures 1 to 4, the latch casing 8 is adapted to be secured to the inner face of the door. S-lidable within the casing is the bolt 9, whose bevelled end protrudes from the fore-end of the casing, the bolt being urged outwardly into the position-shown by a spring Ill. The bolt may be withdrawn by the rotation of a cam ll fast to an operating handle l2, which is rotatably mounted in the casing and is accessible from the inner side of the door. The bolt may also be withdrawn by rotation of a cam l3 rotatably mounted on the cover plate M of the casing and adapted to be connected to the key-operated shaft (not shown) which extends through the,

thickness of the door. The bolt may be retained in either the protruded or the withdrawn position by means of .a sliding catch l'5. The construction thus far described is in accordance with existing practice.

Pivotally mounted in the latch casing upon a pin I6 is a-pawl H. A recess in the pawl slidtively upon the levers 22 and tend to rotate them into the position shown, in which they obstruct inward movement of the restoring bar. The latch casing is formed with a keyway 25 into which "thekey' used for the normal operation of the latch can be inserted from the'inner side of the door. A key inserted in this keyway engages the levers 22 and rotates them on their pivot 9 and have their ends shaped. to-en'gage in cor-, 3 M

'ing portions of the restoring bar 2| and the bar respondingly shaped recesses in the peripheries. of the cams H and [3 respectively. Therecess, in the handle-operated cam H and the end of the arm of pawl H which co-operates with that cam are of dove-tail shape, whilethe recess in the key-operated cam l3 and the end of the cooperating arm of pawl H are of truncated V- shape. It will be seen, therefore, that when the pawl is engaged with the cams, rotation of cam His prevented, but cam 13 can still be rotated and its rotation will operate to return the pawl to the posi'tion'shown. The pawl ll also coinprises a third arm which is formed with two adjacent V -section grooves, either of which can be engaged by a pin 19, spring mounted in the latch casing. This pin serves to retain the pawl, either in the' disengaged position'illustrated, or in the position in which it is fully engagedwith the pawls l I and I3, and gives a snap-over change between the two positions. The projecting end ofthe push rod I8 is inaccessible when the 'door is closed andito guard against its being inadvertently pressed in when the door is open it is protected by-aspring'strip 29 "This'stri-p is anchored at one'end in'a recess formed in the fore-end of the lock casing while its other end is free and can be pressed down to expose the end of thepush rod. I Q

' When the safety device described above is in the position illustrated, the latch will function in the normal manner. On pressing in the projecting end of the push rod [8, the pawl IT is rotated into engagement with the cams I I and 13. This still leaves the bolt S'free to move inwardly in the'casing, so that the door may be closed in the usual way. Rotation of cam H is prevented, so that the bolt cannot be withdrawn by means of the, operating handle l2. Rotation of cam i3 is still possible, however,- so that'the bolt can be withdrawn by means of the key in the usual way andthis operation will also serve to return the parts to the position indicated.

In order to allow the safety device formed by the pawl i1 to be restored to the inoperative position illustrated from the'inner side of the door, there is provided within the latch casing a slidable restoring bar 2f one end of which projects through the wall of the casing. The other end of the restoring bar is adapted to engage the pawl l1, so that when the restoring bar, is slidden inwardly by pressing on its project' ing end, the pawl is returned to the inoperative position illustrated. S-uch inward movement of the restoring bar is, however, normally prevented by two gated levels 22, which are disposed in' slots in the restoring bar. These levers are pivotaily mounted upon a pin 23 which is secured against the action of spring 2 1. When the correct key is in position in the keyway, the gates in the levers are brought opposite the co-operatcan then be. moved inwards to return the pawl '11 to, its inoperative position.

, is formed with a projecting lug 26a adapted to be secured to the side face of the j amb. Within this casing there is disposed a hollow block 2'! which receives, the projecting end of the latch bolt ,9 when the door is closed. The keeper block 2"! is shaped to make interlocking rib and groove engagement with the latch casing 8. To this end the latch casingis formed atits fore-end with a projecting four sided frame 28 which surrounds the bolt 91but leaves the tip of the latter projecting. The top and bottom faces of thisframe are formed with ribs 2% running in the direction of the opening'and closing movement of the door.

The keeper block 2T1 is formed with upper and lowerprojecting jaws 2lc 'whic-h receive between them the projecting frame 28 of :the latch casing, the inner faces of the jaws being formed with grooves which receive the ribs 28a. The

inner ends of the grooves in jaws 21c are tapered, both in plan' andelevation; and the ribs 28a are formed with corresponding taperedportions. The

keeper block 2'! is movable within the keeper casing 26 both vertically and in a direction towards and awayifromthe latch. One side face of the block is pressed into frictional engagement with the inner face of "the casing by a spring friction plate 29. This plate isdispo'sed, in a shallow vertical. groove formed in the opposite side face of the blockand is formed with pressed out spring tongues 29a which engage the adjacent face of the casing.

It will be appreciated that owing to the interlocking engagement of the latch casing and keeper block, any shrinkage or dropping of the door which takes place while the door is closed will result in a corresponding movement of the keeper block within the keeper casing. While the door is open, the keeper block is frictionally retained in the position to which ithas been adjusted. Any slight shrinkage or dropping of the door which may take place while the door is open will not be sufficient in extent to prevent the ribs 28a on the latch casing from engaging in the tapered entry portion of the grooves in the keeper block. Once such engagement is effected, the act of closing the door automatically adjusts the position of the keeper block within the keeper casingto correspond to the new position of. the latch casing. The keeper block is thus maintained in such close coupled relationship with the'keeper casing that no access is possible to the bolt when thedoor is closed, 7 Breaking in by the method of forcing back the protruding end of the bolt is thereby rendered impossible. v r

The side edges of the plate 29 fit closely in the can move only vertically relative to the plate.

' The top and bottom edges of the plate 29 fit closely against the top and bottom of the keeper casing 26, so that the block and plate together can move relative to the casing only in the direction towards and. away from the latch case. Thus, while the block can move relative to the casing in the two directions required, its rotation relative to the casing is prevented. The likelihood of its being accidentally displaced, while the door is open, from the position to which it has been adjusted by engagement with the latch casing is thereby considerably reduced. To facilitate the extraction of the block from the casing (for example to correct such accidental displacement, to effect initial adjustment, or for purposes of repair), grooves 21b are provided in the outer faces of the jaws 21a of the latch block.

I claim:

1. In a door latch, a bolt casing, a bolt reciprocably mounted in said casing to alternately project and retract an end portion with respect to such casing, a keeper casing, a keeper for the reception of the projected end portion of said bolt and adjustably mounted in the keeper casing, means yieldably resisting adjustment of the keeper from positions of adjustment within its casing, and cam-follower and cam components respectively upon the bolt casing and said keeper and cooperable for adjusting the keeper within its casing to effect a desired alignment status of the keeper with respect to the bolt casing pursuant to juxtapositioning of said casings for inserting the bolt into the keeper.

2. A door keeper structure comprising a casing having an open side, upper and lower walls extending from such open side and inner and outer side walls extending between the upper and lower walls and also extending from said open side, a bolt keeper block disposed within said casing and adjustable relatively thereto vertically and also adjustable advancively and retractively with respect to said open side, spring means interposed between said block and one side wall of the casing and pressing the block into frictional engagement with the opposite side wall of the casing, and cam and follower component means on the block and receivable of force for adjusting the block.

3. A door keeper structure in accordance with claim 2, wherein the keeper block has a vertical spring receiving groove within a side thereof in opposed relation to the one side wall of the easing, wherein the spring means is in the form of a spring plate disposed within said groove. the upper and lower edges of said plate engaging said casing to preclude vertical movement of such plate relatively to the casing while facilitating vertical movement of said block relatively to the plate, and said spring plate being horizontally movable to facilitate movement thereof in concert with the block advancively or retractively with respect to the casing opening.

4. A door keeper structure comprising a casing having an open side, upper and lower walls extending from such open side and inner and outer side walls extending between the upper and lower walls and also extending from said open side, a bolt keeper block disposed within said casing and adjustable relatively thereto vertically and also adjustable advancively and retractively with respect to said open side, a side of said block in opposed relation to one side of the side walls of the casing having a vertical groove, a friction plate disposed in said groove to facilitate only vertical movement of the block relatively to such plate, said friction plate being disposed in said casing in frictional engagement therewith for alternate movement only advancively or retractively with respect to the casing opening in concert with the block, and cam and follower component means on the block to receive adjusting force therefor.

5. A door keeper structure according to claim 4, wherein said friction plate is of spring material and is stressed for pressing the block into frictional engagement with the opposite side wall of the casing.

ARCI-IIBALD ROBERTSON MITCHELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,352,010 Lurie Sept. 7, 1920 1,873,528 Anstine Aug. 23, 1932 2,153,080 Flora Apr. 4, 1939 2,246,784 Dall June 24, 1941 2,261,796 Courtney Nov. 4, 1941 2,368,840 Jones Feb. 6, 1945 FOREIGN PATENTS Number Country Date 16,538 Great Britain Nov. 23, 1916 

